Diaphragm switch with volumetrically deformable member



Nov. 15 1966 D. GRIFFITH ETAL 3,286,059

DiAPHRAGM SWITCH WITH VOLUMETRICALLY DEFORMABLE MEMBER Filed July 16, 1964 pm/.440 L @Qwmmf,

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United States Patent Ofiice 3,286,059 Patented Nov. 15, 1966 ,0 DIAPHRAGM SWITCH WITH VOLUMETRICALLY DEFORMABLE MEMBER Donald L. Grifiith, Northridge, Billy E. Nowlin, Mission Hills, and Glen A. Berry,- Granada Hills, Calif., as-

signors to Custom Component Switches, Inc.,- Chatsworth, Califl, a corporation of California Filed July 16, 1964, Ser. No. 383,094 2 Claims. (Cl. 200-83) This invention relates to pressure responsive actuators for electric switches and more particularly to a form thereof adapted to withstand the effects both of high pressures and of corrosive fluids subjected to such pressures.

In Patent No. 3,133,171 dated May 15, 1964' granted to Donald L. Griflith, one of the present applicants, there is shown a pressure switch in which a flexible diaphragm is engaged by the pressure fluid and is caused to actuate the switch through a train of mechanism including a Belleville spring which is caused to partake of snap action with resultant actuation of a switch. The present invention has for its objectives, the provision of an actuating means for a switch m'echanism of the type disclosed in the said patent, which is characterized by adaptation to withstand both extreme pressures and the effects of highly corrosive liquids, which is simple in construction and like in weight with respect to the pressure responsive components thereof and which is highly sensitive to slight changes in pressure.

With the foregoing objects in view, together with such additional objects and advantages that may subsequently appear, the invention resides in the parts, and in the construction, combination and arrangement of parts described, by way of example, in the following specification of a presently preferred embodiment of the invention, ref erence being had to the accompanying drawings which form a part of said specification and-in which drawings:

FIG. 1 is a side elevational view of a pressure switch in which the actuator of the present invention is incorporated,

FIG. 2 is a greatly enlarged fragmentary side elevational view with the actuator of the present invention and the parts of the pressure switch mechanism directly engaged thereby shown in medial section as indicated by the line 22 of FIG; 1.

FIG. 3 is a fragmentary top plan sectional view taken on the line 3"3' of FIG. 2 with portions of the device broken away to disclose construction concealed thereby.

FIG. 4 is a still further enlarged fragmentary medial sectional view showing details of the association with an engagement between the pressure responsive diaphragm of the actuator and the diaphragm cushion means of the actuator, and

FIG. 5 is an end elevational View of the actuator as viewed from the lower end of FIG. 1, the view being on the same scale as FIG. 2.

Referring to the drawings, there is shown a hollow cylindrical switch body 1 having means 2 for connecting electrical leads to one end thereof and means for connecting it to a source of actuating pressure at the opposite end thereof including the body 3 of the actuator of the present invention which is exteriorly threaded and which threadedly engages the interiorly threaded end 4 of the switch body 1. Any suitable means for mounting the switch body may be provided as, for example, the parallel transverse holes 5, 5 for mounting bolts. The switch body 1 encloses a switch and operating mechanism therefor which may be like that disclosed in the said Patent No. 3,133,171, and which may include a disk element D normally held seated in the hollow body 1 by engagement with a Belleville spring B and adapted to be moved in opposition to the bias of the Belleville spring by a riciprocal plunger P guided and actuated by means presently to be described;

The said threaded end 4 of the body 1 terminates in a shallow socket portion 6 of slightly less diameter than the threaded portion 7 thereof in which a guide disk 8 is disposed, said disk having an axially disposed bore 9 affording guidance for a plunger shank S and at the side thereof adjacent the threads 7, terminating in a counterbore 10 in which the head portion H of the plunger P is received, said counterbore being of slightly greater depth than the thickness of the plunger head to define and determine the extent of permissible reciprocable movement of the plunger therein as will presently be discussed. The actuator body 3 is externally threaded to engage the switch body threads 7 and is provided with an end portion 11 to enter the socket 6 at the inner end thereof and with a polygonal (preferably hexagonal) surface 12 at its other end for engagement by a wrench. It is provided with an axially disposed internally threaded bore 13 extending from said outer end thereof toward the distal end 11 affording means for connection with a source of fluid pressure and the inner end of said actuator body is provided with a small axial bore 14 and a plurality of small diagonally outwardly diverging bores 15 extending from the bore 13 to the outer end 11 of the actuator body. The actuator body 3 and a diaphragm to be presently described are the only portions of the device with which the fluid has contact and these parts are therefore formed of a suitable corrosion resistant material such as stainless steel.

The outer end surface 16 of the distal end 11 through which the holes 14 and 15 extend is slightly concave except for a narrow outer rim portion 17 and welded or brazed to this rim portion is the peripheral portion of a thin sheet metal diaphragm 18 preferably having one or more shallow circular ribs or corrugations 19 formed therein to increase the flexibility thereof and the concavity of the actuator body end surface 16 provides clearance so that none of the holes 14 or 15 will be closed by contact of the diaphragm therewith.

Welded or brazed to the outer surface of the outer peripheral portion of the diaphragm 18 is a metal ring 20 having an outer diameter substantially coincident with the outer diameter of the end 11 of the actuator body 3 and an inner diameter somewhat less than the inner diameter of the end surface 17 of the actuator body so that the inner portion of the ring overlies the outer portion of the free portion of the diaphragm. The under face of the ring 20 adjacent to the diaphragm which thus overlies the diaphragm is slightly tapered away from the plane of the diaphragm as shown at 21 in FIG. 4 and the outer end of the ring 20 is finished to be normal to the axial line of the actuator body so as to engage the disk 8 and hold it firmly seated in the bore 6.

H The inner diameter of the ring 20 and the outer face of the diaphragm 18 combine with the face of the guide disk 8 to define a shallow, cylindrical cavity 22 and closely confined within this cavity is a resilient, volumetrically deformable cushion 23 of a plastic composition having flexibility and resilient characteristics similar to a soft rubber. This cushion is initially introduced into the cavity as a viscous fluid containing a catalytic agent which causes it to set. After being introduced into the cavity and before it has set, the fluid is subjected to a high degree of vacuum to remove any trapped and/or entrained air, whereupon, upon being subjected to atmospheric pressure, the fluid will be forced inwardly against the diaphragm and a portion of the fluid will flow into the tapered space between the inner edge of the ring and the adjacent face of the diaphragm forming a thin tapered fin portion 24. In FIG. 4, it will be noted that the juncture of the tapered under face 21 of the ring 20 and the inner peripheral face thereof is slightly rounded. The quantity of the viscous fluid thus introduced in such that upon being set or cured, it will bulge slightly above the end of the ring and this excess is then trimmed off to the plane of the ring.

It will be noted that the entire area of the diaphragm which is external to the fluid contacting side thereof and other than that by which it is fixed to the ring 20 is contacted by this resilient, deformable cushion which also bears against the end of the plunger P as it is pressed downwardly by the spring load on the disk D to the extent determined by seating of the disk on the bottom of the interior of the body 1. So much of the cushion as is not in contact with the plunger head H is in contact either with the outer end surface of the ring 20 or with the adjacent face of the disk 8 so that the diaphragm 18 is thus yieldingly backed up either by the ring 18, the disk 8 or the plunger head H. Since the cushion completely fills the cavity, any pressure induced movement of the diaphragm must result in volumetric displacement of the cushion and since the plunger is the only element other than the diaphragm which can yield and since the plunger is smaller in area than the diaphragm, a given amount of movement by the plunger will require a somewhat lesser extent of diaphragm movement, wherefore in addition to serving as a backup for a thin diaphragm, this cushion serves additionally as a motion multiplying means.

The holes 14 and 15 assure that pressure fluid will contact the entire free area of the diaphragm so that it will be uniformly subjected to fluid pressure. By reason of the fact that it is thus resiliently supported over its entire area, the diaphragm can be formed of very thin flexible stainless steel which may be capable of response to very slight differences in pressure imposed load thereon. When the pressure reaches the magnitude at which switch actuation is intended to take place, the cen ter portion of the diaphragm and the plunger will be moved upwardly as viewed in FIG. 2 with resultant lifting of the disk D against the bias of the spring means opposing such movement and the switch will be actuated by snap action. When the pressure drops to a predetermined magnitude, the switch mechanism will move by snap action in the opposite direction. Alternatively, different weights of steel may be employed in the diaphragms of different actuators which are interchangeable with a given switch assembly so that by selecting an'actuator having a diaphragm of a given resistance to pressure, a given switch apparatus by being combined with an actuator having a selected diaphragm may be constructed to have a diiferent range of operation. Thus by the simple provision of a series of different actuator members, which are relatively inexpensive, it becomes unnecessary to provide a range of switch assemblies all having a different range of pressure response and switch assemblies having a given uniform characteristic can be provided for different pressure situations merely by the selection of a suitable actuator of the present invention.

Thus there has been provided an actuator for pressure actuated switches which is simple in construction and is not affected by the presence of corrosive liquids and which, moreover, is highly sensitive to changes in' the fluid pressure applied thereto. While in the foregoing specification, there has been disclosed a certain presently preferred embodiment of the invention, the invention is not to be deemed to be limited to the precise details of construction thus disclosed by way of example and it will be understood that the invention includes as well, all such changes and modifications in the parts and in the construction, combination and arrangement of parts as shall come within the purview of the appended claims.

We claim:

1. A pressure responsive actuator for a reciprocable plunger component of an electric switch apparatus; said actuator comprising a body member having an externally threaded side surface constituting means of detachable connection to the switch apparatus by engagement with complementary internal threads on the switch apparatus a bore disposed in an end surface of said body member in generally parallel relation to said side surface, means aifording connection of said bore with a source of fluid pressure, a concave surface formed in the end of said body member opposite the end from which said bore extends, a thin flexible metal diaphragm overlying said concave end surface and having the periphery thereof secured to said body member along the periphery of said concave end surface, fluid passage means connecting the interior of said bore with the space defined by said concave end surface and said diaphragm, a volumetrically deformable, resilient means confined at the side of said diaphragm remote from said concave end surface and carried by said body member operative by volumetric deformation thereof in response to fluid pressure induced distention of said diaphragm, to eifect switch actuating movement of a switch actuator engaged by the face of said resilient means which is remote from said diaphragm.

2. A pressure responsive actuator as claimed in claim 1 including a metal ring secured to the side of said diaphragm remote from said concave end surface of said body member and having an inner circumferential edge which is substantially coincident with the outer diameter of the free portion of said diaphragm and combining with said diaphragm to form a shallow, cylindrical recess, and in which a body of volumetrically deformable, resilient material fills said recess and serves upon distention of the diaphragm to actuate the plunger component of the switch on which the actuator is applied.

References Cited by the Examiner UNITED STATES PATENTS 2,787,681 4/1957 Roeser 92-103 X 2,790,043 4/ 1957 Clason 200-83 2,836,671 5/1958 Langstroth 200-83 2,925,986 2/1960 Wood's 92101 BERNARD A. GILHEANY, Primary Examiner. H. M. FLECK, G. MAIER, Assistant Examiners. 

1. A PRESSURE RESPONSIVE ACTUATOR FOR A RECIPROCABLE PLUNGER COMPONENT OF AN ELECTRIC SWITCH APPARATUS; SAID ACTUATOR COMPRISING A BODY MEMBER HAVING AN EXTERNALLY THREADED SIDE SURFACE CONSTITUTING MEANS OF DETACHABLE CONNECTION TO THE SWITCH APPARATUS BY ENGAGEMENT WITH COMPLEMENTARY INTENAL THREADS ON THE SWITCH APPARATUS A BORE DISPOSED IN AN END SURFACE OF SAID BODY MEMBER IN GENERALLY PARALLEL RELATION TO SAID SIDE SURFACE, MEANS AFFORDING CONNECTION OF SAID BORE WITH A SOURCE OF FLUID PRESSURE, A CONCAVE SURFACE FORMED IN THE END OF SAID BODY MEMBER OPPOSITE THE END FROM WHICH SAID BORE EXTENDS, A THIN FLEXIBLE METAL DIAPHRAGM OVERLYING SAID CONCAVE END SURFACE AND HAVING THE PERIPHERY THEREOF SECURED TO SAID BODY MEMBER ALONG THE PERIPHERY OF SAID CONCAVE END SURFACE, FLUID PASSAGE MEANS CONNECTING THE INTERIOR OF SAID BORE WITH THE SPACE DEFINED BY SAID CONCAVE END SURFACE AND SAID DIAPHRAGM, A VOLUMETRICALLY DEFORMABLE, RESILIENT MEANS CONFINED AT THE SIDE OF SAID DIAPHRAGM REMOTE FROM SAID CONCAVE END SURFACE AND CARRIED BY SAID BODY MEMBER OPERATIVE BY VOLUMETRIC DEFORMATION THEREOF IN RESPONSE TO FLUID PRESSURE INDUCED DISTENTION OF SAID DIAPHRAGM, TO EFFECT SWITCH ACTUATING MOVEMENT OF A SWITCH ACTUATOR ENGAGED BY THE FACE OF SAID RESILIENT MEANS WHICH IS REMOTE FROM SAID DIAPHRAGM. 